Ceramic substrate, method of manufacturing the same, and electrical device using the same

ABSTRACT

Provided are a ceramic substrate, a method of manufacturing the same, and an electrical device using the same. A ceramic substrate includes a first laminated body, a second laminated body and an adhesive part. The first laminated body includes a predetermined electrode formed therein. The second laminated body is laminated on and electrically connected to the first laminated body. Also, the adhesive part is intervened between the first laminated body and the second laminated body to adhere the first and second laminated bodies through interfacial reaction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No.2007-0139194 filed on 27 Dec. 2007, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a ceramic substrate, a method ofmanufacturing the same, and an electrical device using the same, andmore particularly, to a composite substrate having excellent electricalproperties and chemical resistance, a method of manufacturing the same,and an electrical device using the same.

2. Description of the Related Art

Generally, a ceramic laminated substrate, especially, a Low TemperatureCo-fired Ceramic (LTCC) substrate, which is fired at a low temperatureof about 1000° C. or less, has excellent electrical properties. Also,LTCC substrate may perform complex functions while realizingultra-miniaturization of a device using the LTCC substrate. Accordingly,LTCC substrate has been widely used in various technical fields.

However, LTCC substrate has a low chemical resistance in spite of theexcellent electrical properties. Accordingly, if used in a certaindevice, LTCC substrate may be melted, especially, during an etchingprocess.

On the other hand, a High Temperature Co-fired Ceramic (HTCC) substrate,which is fired at a high temperature of about 1500° C. or more, hasexcellent mechanical strength and chemical resistance. However, whenhigh temperature ceramic substrate is used in a certain device,implementations of multi-layer and precise pattern may be difficult.Also, high temperature ceramic substrate has weak electrical properties.

Therefore, development of a ceramic substrate capable of embodying amulti-layer structure and a precise pattern with excellent chemicalresistance and electrical properties is required.

SUMMARY OF THE INVENTION

An aspect of the present invention provides to a composite substrate, amethod of manufacturing the same, and an electrical device using thesame, which has excellent electrical properties and chemical resistanceor strength, and may be embodied as a multi-layer structure and aprecise pattern.

According to an aspect of the present invention, there is provided aceramic substrate including: a first laminated body having apredetermined electrode formed therein; a second laminated bodylaminated on and electrically connected to the first laminated body; andan adhesive part intervened between the first laminated body and thesecond laminated body to adhere the first and second laminated bodiesthrough interfacial reaction.

The second laminated body may include a high temperature co-firedceramic substrate.

The first laminated body may include a low temperature co-fired ceramicsubstrate formed from a predetermined ceramic laminated body through alow temperature firing together with the high temperature co-firedceramic substrate.

The adhesive part may include a glass intervened between the ceramiclaminated body and the high temperature co-fired ceramic substrate toprovide a predetermined adhesion through the low temperature firing.

The high temperature co-fired ceramic substrate may include a pluralityof holes, the plurality of holes being filled with an electrode materialidentical to an electrode material of the low temperature co-firedceramic substrate to form an electrode, and being fired together withthe ceramic laminated body.

The first laminated body may include an already-fired low temperatureco-fired ceramic substrate.

The adhesive part may include a glass intervened between the highceramic co-fired ceramic substrate and the low temper co-fired ceramicsubstrate to provide adhesion through a low-temperature firing.

The high temperature co-fired ceramic substrate may include a pluralityof holes, the plurality of holes being filled with a predeterminedmaterial to form an electrode.

The electrode formed in the high temperature co-fired ceramic substratemay be identical to the electrode formed in the low temperature co-firedceramic substrate.

According to another aspect of the present invention, there is providedan electrical device including: a low temperature co-fired ceramicsubstrate having a predetermined electrode formed therein; a hightemperature co-fire ceramic substrate provided on the outside of the lowtemperature co-fired ceramic substrate; an adhesive part intervenedbetween the first laminated body and the second laminated body to adherethe first and second laminated bodies through interfacial reaction; anda working device provided on the high temperature co-fired ceramicsubstrate to perform a predetermined task.

The working device may include a probe device probing each chip in asilicon wafer to test the silicon wafer.

According to still another aspect of the present invention, there isprovided a method of manufacturing a ceramic substrate, the methodincluding: laminating an adhesive part on a first laminated body havinga predetermined electrode therein; laminating a second laminated body onthe adhesive part; and firing the first laminated body, the secondlaminated body, and the adhesive part.

The second laminated body may include a high temperature co-firedceramic substrate.

The first laminated body may include an unfired ceramic laminated body,the first laminated body being adhered to the high temperature co-firedceramic substrate by the adhesive part through the firing.

The first laminated body may include an already-fired low temperatureco-fired ceramic substrate, the first laminated body being adhered tothe high temperature co-fired ceramic substrate by the adhesive partthrough the firing.

The firing may include a low-temperature firing performed within asintering temperature range of the low temperature co-fired ceramicsubstrate.

The adhesive part may include a glass sintered through thelow-temperature firing, the glass providing a predetermined adhesionthrough interfacial reaction with the high temperature co-fired ceramicsubstrate and the low temperature co-fired ceramic substrate,respectively.

Prior to the firing, the method further may include forming a pluralityof holes in the high temperature co-fired ceramic substrate and fillingthe plurality of holes with a predetermined electrode material.

The electrode material filled in the high temperature ceramic substratemay be identical to an electrode material filled in the electrode of thefirst laminated body.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1A through FIG. 1G are a diagram illustrating a ceramic substrateand a method of manufacturing the same according to an embodiment of thepresent invention;

FIG. 2A through FIG. 2F are a diagram illustrating a ceramic substrateand a method of manufacturing the same according to another embodimentof the present invention; and

FIG. 3 is a diagram illustrating an electrical device according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, exemplary embodiments of the present invention will now bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a diagram illustrating a ceramic substrate and a method ofmanufacturing the same according to an embodiment of the presentinvention. A schematic process of manufacturing a ceramic substrateaccording to an embodiment of the present invention is described in FIG.1A to 1G.

The present invention basically relates a composite substrate of a hightemperature co-fired ceramic (HTCC) substrate (hereinafter, referred toas a high temperature ceramic substrate) and a low temperature co-firedceramic (LTCC) substrate (hereinafter, referred to as a low temperatureceramic substrate). FIG. 1 illustrates a method manufacturing a ceramicsubstrate by firing a ceramic laminated body laminated on analready-fired high temperature ceramic substrate at a low temperature.

Referring to FIG. 1A, a high temperature ceramic substrate 20 isprepared. The high temperature ceramic substrate 20 has already beenfired at a high temperature. The high temperature ceramic substrate 20may be provided through a typical HTCC process.

That is, The high temperature ceramic substrate 20 is produced bysintering a sheet formed of alumina and the like at a high temperatureof about 1500° C. or more.

Referring to FIG. 1B, a via hole 21 is formed in the high temperatureceramic substrate 20. The via hole 21 may be formed by a laser, etc.

Referring to of FIG. 1C, an electrode 22 is formed by filling the viahole 21 with a conductive paste.

Compared to an electrode 11 provided in a ceramic laminated sheet 12, aceramic laminated body 13, or a LTCC substrate 10, an electrode in thehigh temperature ceramic substrate 20 is referred to as a secondelectrode 22, and an electrode in the low temperature ceramic substrate10 is referred to as a first electrode 11.

The second electrode 22 may be filled with a material having asubstantially identical physical property to that of the first electrode11.

That is, since fired at a high temperature, a normal high temperatureceramic substrate is formed using a heavy metal such as tungsten ormolybdenum resistant to heat. However, the heavy metal such as tungstenor molybdenum is not preferable because their electrical properties areinferior to copper or argentum.

Accordingly, the electrode may be formed by filling the via hole 21with, but not limited to, copper or argentum in FIG. 1B and 1C.

However, as the case may be, tungsten or molybdenum may be used to formthe electrode while firing the high temperature ceramic substrate in theprocess of manufacturing the ceramic substrate according to anembodiment of the present invention.

If the metal such as tungsten and molybdenum is used in the hightemperature ceramic substrate 20, the processes as described in FIG. 1Band 1C may be unnecessary.

Although the metal such as tungsten and molybdenum is not used, it isnot necessary to equalize the second electrode 22 with the firstelectrode 11. The second electrode 22 may be formed of a material havingsimilar electrical properties to a material forming the first electrode11.

On the other hand, referring to FIG. 1D, a plurality of ceramiclaminated sheets 12 are provided to form the low temperature ceramicsubstrate of the ceramic substrate according to an embodiment of thepresent invention.

Each ceramic laminated sheet 12 includes an electrode formed of copperor argentum, i.e., the first electrode 11. The plurality of ceramiclaminated sheets 12 may be formed of a material, e.g., borosilicateglass, alumina, etc, which is sinterable at a low temperature.

The ceramic laminated sheet 12 may be formed through the followingprocesses. First, a slurry is formed by mixing a ceramic powder with asolvent and a binder. The slurry is coated on a predetermined film anddried into a thin sheet shape. Then, after a via hole is formed in thethin sheet by a laser or a puncher, the via hole is filled with aconductive paste such as copper or argentum to form an electrode. Then,an internal pattern is designed through a screen printing method.

Referring to FIG. 1E, the plurality of ceramic laminated sheets 12 arelaminated on each other to form the ceramic laminated body 13.

Also, a glass 30 is laminated on the top surface or undersurface of theceramic laminated body 13. The glass 30 may be formed of a material,which may be sintered at a temperature substantially identical to orlower than the sintering temperature of the ceramic laminated body 13.

The glass 30 serves to adhere the ceramic laminated body 13 and the hightemperature ceramic substrate 20 to each other while the ceramiclaminated body 13 becomes the low temperature ceramic substrate througha low temperature firing process.

The ceramic laminated sheet 12 may be pressed at a predeterminedpressure to be the ceramic laminated body 13. However, the pressureprocess may be performed at some later time.

Referring to FIG. 1F, the ceramic substrate according to an embodimentof the present invention may be formed by laminating the hightemperature ceramic substrate 20 on the glass 30 laminated on theceramic laminated body 13.

In this case, the high temperature ceramic substrate 20 serves as aconstraint body. That is, when the ceramic laminated body 13 becomes thelow temperature ceramic substrate through the firing process, the hightemperature ceramic substrate 20 serves as a constraint body withoutrequiring any other constraint body to apply a non-shrinkage method.

Generally, when the low temperature ceramic substrate is manufacturedthrough the non-shrinkage method, a separate constraint body islaminated, and removed after the low temperature firing. However, themethod of manufacturing the ceramic substrate according to an embodimentof the present invention does not require the separate constraint body.Accordingly, there is no inconvenience caused by the lamination andremoval of the constraint body.

As described in FIG. 1F, the ceramic laminated body 13, the glass 30,and the high temperature ceramic substrate 20 may be pressed at apredetermined pressure to be united into one body to a certain extent.

On the other hand, when the ceramic laminated body 13, the glass 30, andthe high temperature ceramic substrate 20 are fired at a lowtemperature, only the ceramic laminated 13 and the glass 30 are firedwithout a significant firing effect on the high temperature ceramicsubstrate 20. This is because the high temperature ceramic substrate 20has already been fired at a high temperature.

FIG. 1G illustrates a ceramic substrate completed through the abovefiring processes.

After the ceramic laminated body 13, the glass 30 and the hightemperature ceramic substrate 20 are fired at a low temperature of about1000° C. or less, the ceramic laminated body 13 becomes the lowtemperature ceramic substrate 10, and the glass 30 is combined with thehigh temperature ceramic substrate and the low temperature ceramicsubstrate 10 through interfacial reaction.

Through the firing process, the glass 30 may begin to be fired at asomewhat lower temperature than the ceramic laminated body 13.Accordingly, when the ceramic laminated body 13 is fired, the glass 30provides interfacial adhesions by the interfacial reaction with the hightemperature ceramic substrate 20 and the ceramic laminated body 13.

The glass 30, which begins to be fired at a lower temperature than thefiring temperature of the ceramic laminated body 13, may include B₂O₃,SiO₂, etc.

If the glass 30 is fired at a low temperature after laminated on thehigh temperature ceramic substrate 20 and the ceramic laminated body 13,the glass 30 may buff or prevent a separation or a crack caused by a lowadhesion at an interface between the high temperature ceramic substrate20 and the ceramic laminated body 13.

Referring to FIG. 1G, the ceramic substrate 1 manufactured by the aboveprocess is divided into the high temperature ceramic substrate 20, thelow temperature ceramic substrate 10, and the glass 30 disposedtherebetween.

Accordingly, when the ceramic substrate 1 is used in a device for achemical process, the high temperature ceramic substrate 20 may beallowed to be exposed to an environment requiring a high chemicalresistance due to strong chemical resistance and mechanical strength ofthe high temperature ceramic substrate 20.

Although in such an environment, the excellent electrical properties ofthe low temperature ceramic substrate 10 are usable (an electrodesubstantially identical to that of the low temperature ceramic substrate10 maybe prepared in the high temperature ceramic substrate 20). Also,multi-layer or precise pattern may be embodied in the low temperatureceramic substrate 10.

Brittleness of the high temperature ceramic substrate 20 may be improveddue to its strong mechanical strength. Accordingly, a strong substrateendurable to an external shock can be manufactured.

A ceramic substrate and a method of manufacturing the same according toanother embodiment of the present invention will be described withreference to FIG. 2.

FIGS. 2A to 2F illustrate a method of manufacturing a ceramic substrateby adhering an already-fired high temperature ceramic substrate and analready-fired low temperature ceramic substrate to each other.

Referring to FIG. 2A, a high temperature ceramic substrate 20 isprepared. The high temperature ceramic substrate 20 is an already-hightemperature fired substrate. The high temperature ceramic substrate 20may be provided through a typical HTCC process. Detail description ofthe process will be omitted since it has already been described above.

Referring to FIG. 2B, a via hole 21 is formed in the high temperatureceramic substrate 20 by a laser, etc.

Referring to of FIG. 2C, a second electrode 22 is formed by filling thevia hole 21 with a conductive paste.

The second electrode 22 may be identical to or different from a firstelectrode 11 of a low temperature ceramic substrate, which issubstantially identical to the embodiment as described in FIG. 1.Accordingly, description thereof will be omitted herein.

Referring to FIG. 2D, a low temperature ceramic substrate 10 isprepared, which may be a substrate manufactured by a typical LTCCmethod.

For example, via holes are formed in a plurality of ceramic laminatedsheets. Then, the via hole is filled with a conductive paste to form anelectrode. The ceramic laminated sheets are laminated on each other. Acertain constraint body is laminated on the ceramic laminated sheets.And then, the ceramic laminated body is pressed at a predeterminedpressure, and is fired at a low temperature. Finally, the lowtemperature ceramic substrate 10 may be obtained by removing theconstraint body.

As described in FIG. 2D, a glass 30 is laminated on the top surface orundersurface of the low temperature ceramic substrate 10.

Referring to FIG. 2E, after a glass 30 is laminated on the lowtemperature ceramic substrate 10, the high temperature ceramic substrate20 is laminated on the glass 30. In order to enhance adhesion betweenthem, the low temperature ceramic substrate 10, the glass 30, and thehigh temperature ceramic substrate 20 may be pressed at a predeterminedpressure.

Then, the low temperature ceramic substrate 10, the glass 30, and thehigh temperature ceramic substrate 20 are fired at a low temperature.

In this case, because the high temperature ceramic substrate 30 and thelow temperature ceramic substrate 10 have already been fired, the hightemperature ceramic substrate 30 and the low temperature ceramicsubstrate 10 are not significantly influenced by the low temperaturefiring. On the other hand, the glass 30 and the second electrode 22 ofthe high temperature ceramic substrate 30 are influenced by the lowtemperature firing.

The glass 30 provides interfacial adhesions by the interfacial reactionwith the low temperature ceramic substrate 10 and the high temperatureceramic substrate 30 so as to combine the low and high ceramicsubstrates 10 and 30 into one ceramic substrate 1.

The ceramic substrate 1 according to this embodiment may include a partof the high temperature ceramic substrate 20 having strong chemicalresistance and mechanical strength, and a part of the low temperatureceramic substrate 10. Accordingly, the ceramic substrate 1 may realize adevice capable of performing tasks requiring high electrical propertiesand precision under an environment requiring high chemical resistanceand mechanical strength.

An electrical device employing a ceramic substrate according to anembodiment of the present invention will be described with reference toFIG. 3. A probe card 50 is described as an example of the electricaldevice in FIG. 3.

FIG. 3 illustrates a part of the probe card 50. The probe card 50 mayinclude a PCB 51 mounted with predetermined components, a ceramicsubstrate 1 connected to the PCB 51, and a probe 53 provided on theceramic substrate 1.

The ceramic substrate 1 and the PCB 51 are electrically connected to aconnector 52. Also, a silicon wafer S is shown in FIG. 3.

When each chip of the silicon wafer is probed using the probe card 50,an etching process is required. During the etching process, strongchemical resistance is required due to a long-time exposure to stronglyacidic hydrogen fluoride (HF) solution or strongly alkaline potassiumhydroxide (KOH) solution.

As described in FIG. 3, the ceramic substrate 1 used in the electricaldevice according to an embodiment of the present invention allows thehigh temperature ceramic substrate 30 to be exposed to the silicon waferS, and allows the low temperature ceramic substrate 10 to be positionedtherein. Accordingly, chemical resistance as well as electricalproperties can be improved.

Detail description of the glass 30, a first electrode 11 of the lowtemperature ceramic substrate 10, and a second electrode 22 of the hightemperature ceramic substrate 20 will be omitted because it has alreadybeen described in FIGS. 1 and 2.

The ceramic substrate and method of manufacturing the same according tothe exemplary embodiments has excellent electrical properties, andchemical resistance and strength, and can be embodied as a multi-layerstructure and a precise pattern. Accordingly, it is possible tomanufacture a high-reliability substrate through a non-shrinkage processwithout any constraint body.

While the present invention has been shown and described in connectionwith the exemplary embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

1-11. (canceled)
 12. A method of manufacturing a ceramic substrate, themethod comprising: laminating an adhesive part on a first laminated bodyhaving a predetermined electrode therein; laminating a second laminatedbody on the adhesive part; and firing the first laminated body, thesecond laminated body, and the adhesive part.
 13. The method of claim12, wherein the second laminated body comprises a high temperatureco-fired ceramic substrate.
 14. The method of claim 13, wherein thefirst laminated body comprises an unfired ceramic laminated body, thefirst laminated body being adhered to the high temperature co-firedceramic substrate by the adhesive part through the firing.
 15. Themethod of claim 13, wherein the first laminated body comprises analready-fired low temperature co-fired ceramic substrate, the firstlaminated body being adhered to the high temperature co-fired ceramicsubstrate by the adhesive part through the firing.
 16. The method ofclaim 14, wherein the firing comprises a low-temperature firingperformed within a sintering temperature range of the low temperatureco-fired ceramic substrate.
 17. The method of claim 16, wherein theadhesive part comprises a glass sintered through the low-temperaturefiring, the glass providing a predetermined adhesion through interfacialreaction with the high temperature co-fired ceramic substrate and thelow temperature co-fired ceramic substrate, respectively.
 18. The methodof any of claims 13, prior to the firing, further comprising forming aplurality of holes in the high temperature co-fired ceramic substrateand filling the plurality of holes with a predetermined electrodematerial.
 19. The method of claim 18, wherein the electrode materialfilled in the high temperature ceramic substrate is identical to anelectrode material filled in the electrode of the first laminated body.